Murray, when you are clearing a house room by room, you assume that anyone -I repeat, ANYONE- with a gun is hostile and you shoot them.
PERIOD.
You don't try to take them prisoner unless they are surrendering when you enter the room. In fact if there are no hostages in the building, you throw in a hand grenade first.
You do NOT sacrifice your own men in order to avoid killing terrorists. Since the Russian Army had no way of knowing whether or not the gas had been effective, their shooting of any armed terrorist they came across makes good tactical sense. After all, they could have been playing possum. It's happened before.
Is the SAS scenario that you cited official Royal Army policy or is it merely what you hope that policy is?

troll